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  3. Disable SSH Weak Key Exchange Algorithms

Disable SSH Weak Key Exchange Algorithms

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  • potemkin_aiP Offline
    potemkin_aiP Offline
    potemkin_ai
    wrote on last edited by
    #2

    Pardon, missed the key part:

    The following weak key exchange algorithms are enabled :

    diffie-hellman-group-exchange-sha1
    rsa1024-sha1

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    • potemkin_aiP Offline
      potemkin_aiP Offline
      potemkin_ai
      wrote on last edited by
      #3

      And a few more ssh related configuration things:

      The SSH server is configured to support Cipher Block Chaining (CBC) encryption. This may allow an attacker to recover the plaintext message from the ciphertext.

      The following server-to-client Cipher Block Chaining (CBC) algorithms
      are supported :

      3des-cbc
      aes128-cbc
      aes192-cbc
      aes256-cbc
      cast128-cbc

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      • potemkin_aiP Offline
        potemkin_aiP Offline
        potemkin_ai
        wrote on last edited by
        #4

        and a final piece:

        The remote SSH server is configured to allow either MD5 or 96-bit MAC algorithms, both of which are considered weak.

        The following client-to-server Message Authentication Code (MAC) algorithms
        are supported :

        hmac-sha1-96

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        • necrevistonnezrN Offline
          necrevistonnezrN Offline
          necrevistonnezr
          wrote on last edited by necrevistonnezr
          #5

          https://docs.cloudron.io/security/#securing-ssh-access

          If you use SSH Keys (EdDSA, not RSA!) as per recommendation (although the basic server config is out of Cloudron’s purview) this doesn‘t really matter, I believe….

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          • girishG Offline
            girishG Offline
            girish
            Staff
            wrote on last edited by
            #6

            @potemkin_ai you are free to edit the SSH config as you like. We rely on the default SSHD config (this , in turn comes from your VPS provider and Ubuntu images).

            potemkin_aiP 1 Reply Last reply
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            • girishG girish

              @potemkin_ai you are free to edit the SSH config as you like. We rely on the default SSHD config (this , in turn comes from your VPS provider and Ubuntu images).

              potemkin_aiP Offline
              potemkin_aiP Offline
              potemkin_ai
              wrote on last edited by
              #7

              @girish yeah, I know.

              I wonder why across many similarly configured boxes with the same base ubuntu with the same base sshd only cloudron enabled boxes have that issue.

              And since across multiple boxes with the same base os and configs only cloudron produce that kind of message I reported it here.

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              • girishG Offline
                girishG Offline
                girish
                Staff
                wrote on last edited by
                #8

                @potemkin_ai do you see any change in sshd configs between them? We only add a single comment to sshd.

                potemkin_aiP 1 Reply Last reply
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                • girishG girish

                  @potemkin_ai do you see any change in sshd configs between them? We only add a single comment to sshd.

                  potemkin_aiP Offline
                  potemkin_aiP Offline
                  potemkin_ai
                  wrote on last edited by
                  #9

                  @girish nop. I also checked that, but there are no differences in the configs (apart from the port number)

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                  • girishG Offline
                    girishG Offline
                    girish
                    Staff
                    wrote on last edited by
                    #10

                    @potemkin_ai Is there a way I can run these tests myself?

                    potemkin_aiP 1 Reply Last reply
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                    • girishG girish

                      @potemkin_ai Is there a way I can run these tests myself?

                      potemkin_aiP Offline
                      potemkin_aiP Offline
                      potemkin_ai
                      wrote on last edited by
                      #11

                      @girish sure - just run Nessus full security scan against your server.

                      girishG 1 Reply Last reply
                      1
                      • potemkin_aiP potemkin_ai

                        @girish sure - just run Nessus full security scan against your server.

                        girishG Offline
                        girishG Offline
                        girish
                        Staff
                        wrote on last edited by
                        #12

                        @potemkin_ai No idea what that is. Do you have a link? Is it an online service or something to download ? Also, have you tried asking them about the discrepancy ? If ssh configs are the same, what else could be different?

                        potemkin_aiP 1 Reply Last reply
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                        • girishG girish

                          @potemkin_ai No idea what that is. Do you have a link? Is it an online service or something to download ? Also, have you tried asking them about the discrepancy ? If ssh configs are the same, what else could be different?

                          potemkin_aiP Offline
                          potemkin_aiP Offline
                          potemkin_ai
                          wrote on last edited by
                          #13

                          @girish Nessus is a very old security scanner: https://nessus.org/

                          No ideas, to be honest... that's why I thought to raise it to you.

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